Unambiguity.
Instead of providing a general description of the motions [1]}, [2]}, [3]}, [4]}, [5]}, [6]}, [7]}, we argue that the action classes should be clearly defined and are easy to identify and reproduce. Inspired by the fact that all human actions are the result of muscular contractions, we propose a muscle-driven strategy to systematically design the action set from the perspective of human anatomy. As illustrated in Fig. REF (a)(b), 20 major muscles are identified by professionals in fitness and yoga training, who then put together a list of standard movements associated with these muscles. Moreover, we cross-check with the action definitions from existing datasets [8]}, [3]}, [10]}, [11]}, [2]}, [13]}, [14]}, [15]} to ensure a wide coverage is achieved.
